Pump



INQV. 24, 1942. s, QX' I I 2,302,865

PUMP

. Filed Jan. 16, 1942 (Ittornegs Ritenteci Nov. 24, 1942 UNITED STATESPUMP ' Harry s. Wilcox, Chicago, ni., mimito Hydraulic Controls, Inc., acorporation of Illinois Application January 16, 1942, Serial No. 427,053

Claims.

This invention relates to high pressure displacement pumps andparticularly to pumps in which the cylinders are radially arranged. Y

The invention relates particularly to pumps of the type disclosed in theapplication of Harvey 5 S. Pardee, which since the filing of thepresent;- application issued as Patent No. 2,271,570 on February 3,1942, under which applicant's assignee is operating. In the Pardee pump,an

even number of single acting cylinders (usually four or eight) are used,and these cylinders are oiiset from true radial lines in a directionopposite to the direction of rotation of the drive shaft. The driveshaft carries an eccentric on which a sleeve is rotatably mounted bymeans 16 of a'needle bearing. Between the sleeve andeach pump plunger isa crescent shaped slipper which offers a concave cylindrical bearingcontacting the sleeve and a convex cylindrical Journal which is receivedin a concave cylindrical :0

bearing machined across the inner end of the plunger. Flanges at theends of the journal on the slipper limit motion of the slippers in thedirection of the axis of the sleeve.

A plurality of bow or arcuate wire springs con- 20 nect opposed plungersin pairs, and flex slightly as the pump runs, to accommodate slightdifferences in the instantaneous velocities of the two opposed plungers,such diflerences being entailed by the geometry of the crank andconnecting rod couples comprising the eccentric and each slipper.

In the Pardee pump the slipper is not positively connected either to thesleeve or to the plunger.

' On the contrary, the assembled relation is maintained by the springswhich are mounted under suiiicient initial tension to ensure that theparts will be held in close engagement at all times. This impliessuiilcient tension to pull the plunger through its suction stroke andmaintainunder 40 all conditions a thrust engagement with the slipper.

In commercial pumps having plunger strokes and cylinder bores each ofthe order of inch,

this action is consistently secured, as evidenced by oscillographstudies, at speeds up-to at least 3500 R. P. M. though the usualoperating speed is 1750 R. P. M. At such speeds the pump has goodoperating characteristics delivering against discharge pressures from2500 to 3000 per square inch.

Obviously precise manufacture, the elimination of excess weight in theplungers, and the use of excellent heat treated material are essentialto sustained performance because inertia eflects 55 pounds aresubstantial and unit pressures are high. The

bearing area between slipper and plunger cannot be increased, beingcoextensive with the end of the plunger. Use 01' a simple cylindricalplunger is dictated by the requirements of precise manufacture atreasonable cost. Indeed, many features'of the design are critical to anextent not obvious at first glance.

Failure 0! .a spring, which has proved to be a rare occurrence, releasestwo slippers. Contrary to what might be expected, this does notnecessarily wreck the pump, but it does involve serious risk.

Connection of the slipper with the pump.

' January 16, 1942, and assigned to applicant's asj signee, involves theuse of a slender wire stirrup which embraces the slipper and engages theplunger. Because such a stirrup cannot be located so as to operateaccurately as a swinging link, it is maderesilient and is mounted understress so that it urges the slipper toward the plunger.

The object oi the present invention which was conceived as animprovement on the Huber invention is to provide a more rugged sheetmetal clip which engasrs an arcuate groove in the slipper, the are beingconcentric with the plunger ens s ns journal in the slipper. Thus, theclip is simply a retainer and has no spring action. It has no activefunction in the normal operation of the pump, but prevents the escape ofa slipper if its plunger tends to stick slightly during the suctionstroke. Also it retains the slipper in the event of breakage of across-connecting spring and thus minimizes the danger of wreck:

ing the pump.

.Critical factors in the design of pumps of this type impose the use ofvery small clearances, a fact which greatly complicates the problem ofdeveloping asmall and rugged attachment. Two somewhat similarembodiments which meet practical requirements will now be described byreference to the accompanying drawing, in which:

Fig. 1 shows a commercial eight cylinderpump with the front cover plateremoved to show the invention applied. The pump is shown approximatelyfull size in the Patent Office drawing as filed.

Fig. 2 is a fragmentary section on the line 2-2 of Fig. l, the scalebeing twice that of Fig. 1.

Fig. 3 is a further enlarged view .of a part of the plunger and slipperas viewed in Fig. 1.

Figs. 4 and 5 are an elevation and plan of the clip before applicationto the plunger.

Fig. 6 shows a blank for forming a modified type of clip.

Fig. '7 is a perspective view of the clip formed from the blank shown inFig. 6.

Referring first to Fig. 1, 6 represents the body of the pump which isprovided with an inlet connection 'l and a discharge connection 8 and aplurality of radial bosses 9 which house the cylinder bushings ll. Eightsuch bosses are shown in Fig. 1, the pump being of the eight cylindertype. The bosses 9 are bored to receive cy'inder bushings H which arepressed to place and seat against shoulders l2. The housing 6 isprovided with passages l3 which communicate with the inlet passage 1 andwith inlet ports I which are drilled in the bushings II and which areexposed by the plunger l5 when the plunger l6 moves radially inward toits limit of motion.

The discharge chambers I6 all communicate with the discharge connection8. Cup-shaped discharge valves ll of generally cylindrical contour areurged inward, that is, in a closing direction by coil compressionsprings i8, whose inner ends are housed within the cup-shaped valves Hand whose outer ends are received in sockets in the screw plugs I9, oneof which is screwed into each of the bosses 9. Each valve 11 seatsagainst the outer end of the corresponding bushing II and the parts areso dimensionedthat at the extreme outer limit of motion of each plungerIS, the plunger engages the valve l1 and holds it off its seat. Thisposition is shown in Fig. 2.

The pump shaft appears at 2! and carries keyed to it an eccentric 22. Inthe example illustrated, it is understood that the shaft 2| turnscounterclockwise, and it will be observed that the axis of each of thecylinder bushings H is offset clockwise slightly from a line radial tothe center of shaft 2|.

The shaft 2| is mounted in bearings of the ball type, one of whichappears at 23. These bearings are mounted in the main housing 24 of thepump, only a fragment of which appears in Fig. 2.

In an eight cylinder pump there are four such springs and the lengths ofthe hooked ends 3'! are differentiated so that the springs may overlapwithout interference, as clearly indicated in Fig. 1. Because of thebowed configuration of the springs they are out of the orbit of thesleeve 25.

So far, the pump conforms to the Pardee design and no novelty for thepump is here claimed.

The present invention provides means for retaining each slipper inoperative relation with its plunger. The length of the bushings ll,necessary to ensure adequate guiding of its plunger [6, is such that theminimum clearance between the end of the bushing and the slipper issmall. Furthermore, since these pumps operate at high speeds and againsthigh discharge pressures, the unit pressure between the plunger I6 andthe slipper 22 is high and it is desirable 'to maintain a thrustengagement between these two parts across the entire transverse area ofthe plunger.

According to the preferred form of the invention which is illustrated inFigs. 1 to 5 inclusive, use is made of a clip whose form is best shownin Figs. 2 to 5. The clip takes the form of an octagonal disc or plate36, and this disc as initially formed, has a central aperture 36 havinga serrated margin producing a series of inwardly extending fingers ll.Before the application of the disc to the plunger, these fingers 4| arecurled upward, as best shown in Figs. 4 and 5. The disc carries twoopposed pendant arms 42 with inturned lugs 43 (see Fig. 4). A shortdistance above the bearing 29 the plunger i6 is provided with acircumferential groove 44 of moderate depth and the clip is applied tothe plunger by slipping it over the plunger until the fingers 4| canenter the groove 44 after which the fingers are bent back into the planeof the disc 28, as shown, for example, in Figs. 2 and 3. This fixes thedisc on the plunger so that the two move as a unit in the direction ofthe axis of the plunger.

Mountedon the eccentric 22 is the sleeve 26 and interposed between thesleeve and the eccentric are a series of bearing rollers 26 whichbecause of their small diameter relatively to their length, form what iscommonly known as a needle hearing. The needles are confined by thediscs 21 and 26. Each of the plungers I6 is formed at its inner end withan arcuate seat 28 which is machined across the entire inner end of theplunger and seats on a convex cylindrical journal 3l which is formed onthe slipper, generally indicated by the reference numeral 32.

As a convenient means for limiting the motion of the slipper in 'adirection transverse to the plunger l5, flanges 33 are provided at thetwo ends of the slipper. The lower face of the slipper is formed with aconcave cylindrical bearing 34 which fits the cylindrical sleeve 25already mentioned. The inner ends of the bushings II are slotted asindicated at 35 and opposed plungers I6 are connected together by crossconnecting springs 36. These have hooked ends 31 which enter sockets 40bored in the plungers l5 and work in the slots 35. These sockets aredrilled at a slight angle, as best indicated in Fig. 2, so that thesprings retain themselves. The construction causes the bushing to guidethe plungers close to the eccentric and slippers and the slots guide thesprings 36.

clip is not a complete annui v at 46 so that it may be opened s ightlyand sprung Slipper 32 is provided on its two end or plane faces witharcuate grooves 45 which receive the inturned lugs 43, alreadydescribed. Obviously the slipper may be brought into engagement with thelugs 43 by a rotary motion after which the clip serves to retain theslipper in position against the bearing 28. The clip is not loadedduring the normal operation of the device, butunder the conditionsabovestated, the clip retains the slipper in engagement with the end of theplunger so that it will not drop away and become jammed in other movingparts of the pump.

The modification shown in Figs. 6 and 7 is believed to be inferior, butreasonably satisfactory.

- The finished clip takes the form of a stamping having an annularsection 38a with inwardly projecting fingers lla surrounding the centralaperture 360. The blank from which the clip is formed is illustrated inFig. 6. The clip carries pendantarms 2a with inturned fingers 30. Beingformed from a fiat strip, as indicated, the but is separated over theend of the plunger l6 until the fingers Ila can enter the groove 44.While the type of clip shown in detail in Figs. 4 and 5 is preferred,the clip shown in Figs. 6 and 'I has sufficient strength for mostpurposes and when used performs the same function as the preferred formof clip.

The invention has the advantage that the clip is comparatively rugged;it can be used with clearances now standard in commercial pumps and doesnot reduce the bearing area between the slipper and the plunger or thebearing area between the slipper and the sleeve. Furthermore, becausethe clip is free to rotate on the plunger and because the arc of itsengagement with the slipper groove is small, the clip leaves the slippersufliciently free to assume proper alinement. The slipper is not subjectto load in the normal operation of the pump and it is ample to retainthe slippers in engagement with the pump plunger upon failure of a crossconnecting spring, or in the event that a piston sticks slightly duringthe suction stroke.

While two embodiments of the invention have been described inconsiderable detail, their specific forms are prescribed by criticaldesign factors in the particular pump chosen for illustration.

Modifications within the general scope of the invention are possible andare contemplated and may be dictated in the case of pumps of somewhatdiilerent design. Consequently the description above given is intendedto be exemplary engaging arcuate guiding means formed in the ends of theslipper concentrically with the axis of the journal on the slipper; andyielding means urging said plunger radially inward and serving tomaintain thrust engagement between eccentric, slipper and plunger.

2. The combination defined in claim 1 in which the plunger is of simplefi lindrical configuration and the swivel connection between plunger andretainer comprises a circumferential groove on the plunger which securesand confines portions of the retainer.

3. The combination defined in claim 1, in which the plunger is formedwith a circumferential groove and the retainer comprises a continuousencircling annulus formed with lugs confined in said groove.

4. The combination defined in claim 1 in which the guiding means on theends of the slipper are arcuate grooves, which are engaged by intumedportions of arms, formed on the retainer and straddling the slipper.

5. In an eccentric-driven radial pump, the combination of a rotaryeccentric; at least two substantially radial plungers -mounted inopposed relation and each having a cylindrical bearing formed across itsinner end; slippers one for each plunger, each slipper having a bearingengaging the eccentric and an opposed journal engaging the bearing on acorresponding plunger; means for connecting each slipper with itsplunger, said means comprising a retainer swiveled on the plungeradjacent the inner end thereof and having extensions engaging arcuateguiding means formed on the ends of the slipper concentrically with theaxis of the journal on the slipper; and yielding means mounted understress and serving to connect said opposed plungers in pairs.

- HARRY'S. WILCOX.

